Cummins Fault Code 7286

Circuit Description

Normally, switches, accelerators, and other components are connected to the engine control module (ECM) directly through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic control unit (VECU) or transmission electronic control unit (ECU) in the cab. Then component values and states from components such as sensors, accelerators, and switches can be transmitted from the OEM VECU to the Cummins ECM over the SAE J1939 data link.

Messages sent from OEM VECUs or transmission ECUs are received by the Cummins ECM and used for controlling the engine. The Cummins ECM and OEM VECUs must be configured properly so that proper operation of the multiplexed components will occur.

Component Location

The SAE J1939 data link wiring and the SAE J1939 devices vary by OEM options.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) did not receive a message from a multiplexed device.

The Engine Control Module (ECM) detected an open or short circuit condition in the J1939 data link harness.

Action Taken When the Fault Code is Active

• The ECM logs the fault code immediately when the diagnostic runs and fails.

The multiplexed device will not operate.

Conditions for Clearing the Fault Code

• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The “Reset All Faults” command in the recommended Cummins electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk

When this fault code is active, some multiplexed devices can possibly not function as desired.

This fault can occur for the following reasons:

• When the ECM is set up properly (components enabled and OEM VECU or transmission ECU source addressed correctly) to receive information from an OEM VECU or transmission ECU, but the OEM VECU or transmission ECU is actually transmitting a message that says that component is not available for multiplexing. This can be caused when a multiplexed component is enabled in the ECM, but the OEM VECU or transmission ECU source address of the VECU or transmission ECU transmitting the component message is incorrect in the Cummins® ECM, or the OEM VECU or transmission ECU is not set up to transmit the multiplexed component message.
• This fault can also be caused by a damaged J1939 data link connection between the OEM VECU or transmission ECU and Cummins ECM, a damaged connection between the component and the OEM VECU or transmission ECU, damaged OEM VECU, transmission ECU, or damaged Cummins ECM. It can become necessary to contact the OEM or Transmission supplier for proper multiplexing configuration.

It is possible to use the recommended Cummins electronic service tool or equivalent to monitor multiplexed components.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.